Process of making pulverulent metallic titanium



PROCESS OF MAKING PULVERULENT METALLIC TITANIUM Jean Cueilleron, Lyon, Charles Long, Saint-Geuis-Laval, and Claude Pascaud, La Reole, France, assignors to Societe dElectro-Chimie dElectro-Metallurgie et des Acieries Electriques dUgine, Paris, France No Drawing. Application March 13, 1953, Serial No. 342,286

Claims priority, application France March 19, 1952 3 Claims. (Cl. 75-.5)

This invention relates to a process of making pulverulent metallic titanium from titanium-aluminum alloys.

It is known to produce titanium-aluminum alloys for example by alumino-thermic reduction of titanium oxide, the aluminum being employed, for instance, in the form of shot. In carrying out the alumino-thermic reduction it is advantageous to use lime, which forms with the nascent alumina a calcium aluminate slag protecting the metal during the reaction and the cooling.

According to the present invention, pulverulent metallic titanium is made by treating titanium-aluminum alloy, made by any desired process, with a reagent which attacks the aluminum but does not substantially attack the titanium. Preferably the reagent is an aqueous alkaline solution, a particularly suitable solution being an aqueous soda solution. Such solution attacks the aluminum, giving a sodium aluminate solution, but leaves the titanium substantially unaltered. In place of a soda solution, we may use a solution of sodium hydroxide, potassium carbonate or potassium hydroxide.

The titanium-aluminum alloys which give the best results are those containing about 40 to 65% of titanium and about 60 to 35% of aluminum. However, compositions outside of these ranges can be employed but produce less desirable results. In any case, the composition of the alloy should be such that when treated with a reagent which attacks the aluminum it does not substantially attack the titanium.

It is particularly desirable to subject the titanium-aluminum alloy to a violent cooling from its molten condition as produced. This may be done, for example, by applying an abundant supply of water to it or by quenching it in water. Such violent cooling produces a structure in the solidified alloy which makes it easier to dissolve the aluminum from the alloy by means of an alkaline solution without substantially attacking the titanium. In addition, the violent cooling causes the solidified alloy to become brittle, which promotes its pulverization.

The strength of the aqueous alkaline solution employed is not of great importance in the results obtained. However, other conditions being equal, the higher the concentration of the alkaline solution, the more rapid is the attack of the solution on the aluminum of the alloy.

The process can be carried out in the following manner.

A titanium-aluminum alloy is crushed, ground, and passed through a sieve of 1296 meshes per square centimeter. It can be passed through a sieve of 117 or 324 meshes per square centimeter, but the duration of the attack by the alkaline solution is considerably longer in such case.

The shifted alloy is treated with an aqueous solution of soda at the boiling point of the solution (a little above 100 C.). The duration of the treatment until almost complete elimination of aluminum is accomplished varies according to the grain size of the powder and the concentration of the soda solution. For an alloy passed through a sieve of 829 meshes per square centimeter, for example, this time is about 8 hours for a soda solution nited States atent ii 2,750,271 Patented June 12, 1956 having a concentration of 6% by weight, and about 2 hours for a soda solution having a concentration of 10%.

'After the treatment to dissolve the aluminum is completed,

the titanium powder is filtered from the solution. The titanium powder usually contains a small amount of aluminum and an amount of oxygen, rather variable, usually within the range of 1 to 5%. This oxygen is in a hydrous form of titanium oxide, believed to be fixed on the surface of the titanium particles. Such oxide can be largely removed, according to the invention, by washing the titanium powder with a dilute acid, for example, hydrochloric acid, sulphuric acid, nitric acid, hydrofluoric acid, or a mixture thereof, at an acid concentration of a few hundredths per cent by weight. By this means the oxygen content can be lowered to a very small value. The applicants have thus obtained titanium powder containing 0.27% oxygen.

The following examples further illustrate the invention:

Example 1 Titanium-aluminum alloy containing:

Percent Titanium 43.08

Aluminum 56.00

Oxygen 0.90

was crushed, ground and passed through a sieve of 207 meshes per square centimeter and the powder so obtained was treated with a soda solution at the boiling point of the solution and having a concentration of 5% by weight. After 24 hours, a fine metallic powder of the following composition was obtained:

was crushed, ground and passed through a sieve of 207 meshes per square centimeter and the powder so obtained was treated with a soda solution at the boiling point of the solution and having a concentration of 8% by weight. After 8 hours a fine metallic powder of the following composition was obtained:

Percent Titanium 97.00

Aluminum 2.00

Oxygen 1.00

The same result was obtained by treating the same titanium-aluminum alloy for 2 hours with a soda solution having a concentration of 10% by weight and heated to its boiling point.

The titanium powder, after separating it from the solution, was deoxidized by washing it for 5 minutes in a sulphuric acid solution at a concentration of 5 by weight or in a mixture of equal parts of sulphuric acid having a concentration of 10% and hydrofluoric acid having a concentration of 1%. In each case the powder was washed with water after the acid washing. The proportion of oxygen was lowered in this manner to about 0.3%.

The invention is not limited to the preferred embodiment but may be otherwise embodied or practiced within the scope of the following claims.

We claim:

1. The process of making pulverulent metallic titanium, which comprises violently cooling a molten mass of alloy 4 composed of 40-60% titanium and 35-60% aluminum, References Cited in the file of this patent powdering the alloy and treating the alloy powder with UNITED STATES PATENTS an aqueous alkaline solution which attacks the aluminum but does not substantially attack the titanium for a period 1,628,190 Raney May 1927 of time sufiicient to dissolve substantially all of the alu- 5 2,299,228 Gray 1942 ma lin; d t l 1 h th OTHER REFERENCES e a u 6 process accor mg 0 c alm W erem q 6 Technical Information on Titanium Metal. Pages 20 ous alkaline solution is a soda solution.

3. The process according to claim 1 wherein the puland Revlsed March 1949- Publlshed by verulent titanium is washed with an acid solution to 10 ington Arms Bridgeport, connecficjltremove oxygen fixed on the surface of the titanium par- Journal Of Metals, 1952, TfaIlSaCflOHS, M- ticles. pages 70 and 71. 

1. THE PROCESS FOR MAKING PULVERULENT METALLIC TITANIUM, WHICH COMPRISES VIOLENTLY COOLING A MOLTEN MASS OF ALLOY COMPOSED OF 40-60% TITANIUM AND 35-60% ALUMINUM POWDERING THE ALLOY AND TREATING THE ALLOY POWDER WITH AN AQUEOUS ALKALINE SOLUTION WHICH ATTACKS THE ALUMINUM BUT DOES NOT SUBSTANTIALLY ATTACK THE TITANIUM FOR A PERIOD OF TIME SUFFICIENT TO DISSOLVE SUBSTANTIALLY ALL OF THE ALUMINUM. 